Clamping device for a tool

ABSTRACT

A clamping device for a tool being joined to a machine includes a clamping member and a fitting ring. Thickness of the fitting ring being greater than a length between the conical part and the holding part of the clamping member allows the machine pressing against the fitting ring in case of the machine clamping the conical part with more steady clamping and achieving an effect of cushion.

FIELD OF THE INVENTION

The present invention relates to a clamping device for a tool being mounted to a machine and particularly to a clamping device, which provides a fitting ring for cushioning and assisting the tool being clamped.

BACKGROUND OF THE INVENTION

Generally, the CNC (computerized numerical control) machine has been indispensable for work pieces being machined with operations such as drilling, reaming, boring and milling. Cutting tools are usually mounted to the machine with the tool handle or tool stem thereof being joined to the spindle of the machine respectively. The tool handle has a taper part at the front end thereof for being clamped by the machine and the rear end thereof is for being attached to the cutter such that the cutting tools are able to be held to the machine.

The taper part provides an advantage that precise dimension of the respective tool handle for accommodating different machines is not required and the taper part slants gradually for being inserted into the machine to form a best fit during clamping being performed. Hence, it is suitable for different machines and achieving tight fit assembly even if there is dimensional error resulting from production tool because the error is adjusted easily.

However, the preceding arrangement has a problem that the rear end is in a state of suspending without contacting with the tool handle due to only the taper part of the tool being clamped. In this way, it is very easy for the tool to occur a phenomenon of swinging and to influence precision of machining seriously.

In order to solve the preceding problem, prior art such as disclosures of U.S. Pat. Nos. 5,352,073 and 6,739,810 has proposed many ways for improvement and the most desirable way is to change clamping part of the machine tool, that is, a press part is provided at the rear end of the machine to press against the tool handle for enhancing steadiness during the tool handle being clamped. This is so-called “Dual Contact”. But, another problem is created that structure of the machine has to be changed and it is a puzzle to the manufacturers because the original machine has to be sent back to the shop for revising the structure thereof or replacing new parts. Further, in casing of the revised structure, especially the press part, being redesigned improperly, another big problem has to be faced undesirably.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a clamping device for a tool, which is capable of assisting support of a clamping member and providing a function of cushion for offering much better steady machining condition and promoting machining precision.

In order to achieve the preceding object, the clamping device for a tool according to the present invention includes a clamping member and a fitting ring with the clamping member having a conical part at an end section thereof for being clamped with the machine, a holding part, which extends outward circumferentially, at a middle section thereof, and a retaining recess at another end section thereof for fixing with a tool and the fitting ring passing over the conical part and being attached to a lateral side of the holding part for the machine pressing against the fitting ring in case of the machine clamping the conical part for assisting support of the clamping member and providing a function of cushion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reference to the following description and accompanying drawings, in which:

FIG. 1A is an exploded perspective view of a clamping device for a tool according to the present invention;

FIG. 1B is an exploded sectional view of a clamping device for a tool shown in Fig. FIG. 1A;

FIG. 2A is a plan view of a clamping device for a tool according to the present invention;

FIG. 2B is a sectional view of the clamping device shown in FIG. 2A; and

FIG. 3 is a sectional view illustrating the clamping device for a tool according to the present invention being joined to a worktable on a machine.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1A and 1B, a clamping device for a tool according to the present invention includes a clamping member 10 and a fitting ring 20. The clamping member 10 has a conical part 12 at the front section thereof, a holding section 14, which extends outward circumferentially, at the middle section thereof, and a retaining recess 16 at the rear section thereof. The retaining recess 16 is capable of connecting with a tool such as a milling cutter or a drill on the CNC machine and the conical part 12 is joined to the machine. The fitting ring 20 basically is a circular ring with an inner diameter slightly greater than the diameter of the outer end of the conical part 12 and slightly less than the outer diameter of the holding part 14 such that the fitting ring 20 is able to be attached to the holding part 14 directly via passing over the outer end of the conical part 12 without falling down.

Referring to FIGS. 2A and 2B, the fitting ring 20 is attached to the lateral side of the holding part 14 for being forcedly contacted with the machine (details will be explained afterward). Alternatively, other joining ways such as adhesives, projections and grooves can be used in order to locate the fitting ring 20. These are variations can be achieved easily by persons in the art and no detail will be described further.

Referring to FIG. 3, an end of the machine 30 is disposed against the fitting ring 20 instead of the conventional device being in a state of suspension. Hence, it is capable of increasing steadiness during the machine running and machining the work piece. In order to secure the machine 30 keeping in a state of pressing against the fitting ring 20, the fitting ring 20 is arranged to provide a thickness thereof greater than the horizontal section of a conjunction between the inner end of the conical section 12 and the holding part 14. Further, it is preferable that the fitting ring 20 is made of soft metal such as aluminum to provide a function of cushion with certain strength.

It is appreciated that the fitting ring of the clamping device for a tool according to the present invention overcomes deficiency of the conventional clamping device substantially even if the fitting ring is mounted to a conventional CNC machine without changing structure of the machine.

While the invention has been described with reference to a preferred embodiment thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention, which is defined by the appended claims. 

1. A clamping device for a tool being fixed to a machine, comprising: a clamping member, having a conical part at an end section thereof for being clamped with the machine, a holding part, which extends outward circumferentially, at a middle section thereof, and a retaining recess at another end section thereof for fixing with a tool; and a fitting ring, passing over the conical part and being attached to a lateral side of the holding part for the machine pressing against the fitting ring in case of the machine clamping the conical part.
 2. The clamping device as defined claim 1, wherein the fitting ring is a circular ring.
 3. The clamping device as defined in claim 1, wherein the fitting ring is made of metal.
 4. The clamping device as defined in claim 3, wherein the fitting ring is made of aluminum.
 5. The clamping device as defined in claim 1, wherein fitting ring is adhered to the holding part.
 6. The clamping device as defined in claim 1, wherein the fitting ring is attached to the holding part with pins.
 7. The clamping device as defined in claim 1, wherein the fitting ring provides at least an extending outward secure part and the holding part has a recess corresponding to the secure part for engaging with each other.
 8. The clamping device as defined in claim 1, wherein a horizontal section is formed between the conical part and the holding part and the fitting ring provides a thickness greater than length of the horizontal section. 